Apparatus for sensitive measurement and recording of physiological activity

ABSTRACT

An apparatus for sensitive measurement and recording of the responses and activity in a biological specimen useful for the toxicological and pharmacological investigation of drugs, chemicals and gaseous environments. The apparatus includes an environmental chamber in which a biological specimen is stereotaxically mounted for positioning in selectable engagement with the probe of a piezoelectric transducer. The atmosphere within the chamber may be controlled to provide a particular gas within the chamber such as a contaminated or polluted air environment. The physiological activity or responses of a specimen to a selected gas or to manually administered drugs or chemicals are measured by the transducing device. The signal is then suitably amplified, filtered, processed and controlled to provide a visual or auditory recording of the processed signal.

United States Patent Pence [54] APPARATUS FOR SENSITIVE MEASUREMENT ANDRECORDING OF PHYSIOLOGICAL ACTIVITY [72] lnventor: Roy J. Pence, LosAngeles, Calif.

[73] Assignee: The Regents of the University of California, Berkeley,Calif.

[22] Filed: Dec. 14, 1970 [21] Appl. No.: 97,617

[52] US. Cl. ..73/432 R, 128/2 N [51] Int. Cl. ..A6lb 10/00 I [58] Fieldof Search ..73/432 R, 432 SD; 128/2 R, 128/2 N [56] References CitedUNITED STATES PATENTS 1,827,530 10/1931 Le Grand ..73/432 SD UX FOREIGNPATENTS OR APPLICATIONS 650,542 2/1951 Great Britain ..l28/2 N 1 Nov.21, 1972 Primary Examiner-Louis R. Prince Assistant Examiner-Joseph W.Roskos Attorney-Miketta, Glenny, Poms 8r Smith [57] ABSTRACT Anapparatus for sensitive measurement and recording of the responses andactivity in a biological specimen useful for the, toxicological andpharmacological investigation of drugs, chemicals and gaseousenvironments. The apparatus includes an environmental chamber in which abiological specimen is stereotaxically mounted for positioning inselectable engagement with the probe of a piezoelectric transducer. Theatmosphere within the chamber may be controlled to provide a particulargas within the chamber such as a contaminated or polluted airenvironment. The physiological activity or responses of a specimen to aselected gas or to manually administered drugs or chemicals are measuredby the transducing device. The signal is then suitably amplified,filtered, processed and controlled to provide a visual or auditoryrecording of the processed signal.

3 Claims, 3 Drawing Figures PATENTED NOV 2 1 I972 INVENTOR. I R04 1]:PEA CE BY PEN 67/0/27 RECORDER flag. AIM

APPARATUS FOR SENSITIVE MEASUREMENT AND RECORDING OF PHYSIOLOGICALACTIVITY BACKGROUND AND PRIOR ART At a time of increased socialconsciousness of environmental problems, a corresponding increase hasarisen in the need for new methods and tools of basic research onphysiological responses of organisms for external sources. The study ofthe interaction between atmospheric pollution and biological systems hasresulted in a closer relationship between the entomological andtoxicological disciplines. Simultaneous with the advent of growth inecological concern there has appeared an increased interest by medical,pharmaceutical and governmental bodies in the biological effects of theuse, and abuse, of drugs, pesticides, and the like. This area of socialanxiety has also placed further burdens on the efforts to develop moreeffective research tools and techniques in the fields of physiology andpharmacology.

In response to these demands, investigations have been made regardingthe physiological similarities between insects and higher organismswhich involves the measurement of physiological activity of a simplebiological system. It has been found that regardless of themorphological differences between insects and higher animals, there arebiological and physiological similarities which make the insectssuitable for testing, particularly in view of their short life cycle andnatural abundance. One nearly ideal bio-assay system for study is theexcised honeybee abdomen. Such abdomens, selected so as to have emptycrops, may be carefully severed from the thorax, at the pedicel, whenthe living bees have been anesthetized with CO gas. The resultingspecimen will constitute an unstressed biological system maintainingsteady pulsitive activity for at least 24 hours. The abdomen is highlyresponsive to airborne molecules or injections (through the alimentarycanal which is simultaneously bathed externally by hemolymph containingthe same substance). Airborne molecules have been found to rapidly enterthe spiracles and tracheae of the respiratory system and then into theblood. All routes of administration immediately trigger neuromuscularresponse.

Having found the extreme sensitivity and responsiveness of the excisedhoneybee abdomen to its ambient environment or to chemical or drugadministrations, it became apparent that suitable equipment would berequired to measure and record the precise nature of this physiologicalactivity. Two interrelated problems became immediately apparent. First,a high sensitive sensing system would be required, probably involvingequally sensitive electromechanical transduction amplification andrecording. Second, an appropriate chamber would be needed to isolate thespecimen from undesirable sounds, vibrations, gases, temperaturechanges, etc. Only through the integration of these desideratum could asuccessful interface between the biological system and the dataacquisition system be accomplished.

SUMMARY OF THE INVENTION It is therefore an object of the presentinvention to provide electro-mechanical means for sensitive measurementand recording of the physiological activity of a biological systemstimulated by substances which may be airborne or injected to produce aresponse therein. It is another object of the present invention toprovide a sensing and measuring means for acquiring data regarding abiological specimen and including means for isolating such specimen froma plurality of uncontrolled variables, including temperature, changes inthe gaseous environment in which the specimen is maintained, variationin acoustical level, etc. It is a more particular object of the presentinvention to provide electro-mechanical transducing means for sensingphysiological changes in a bio-assay system, amplifying the resultantsignals, selecting the particular signal frequencies desired, processingsuch signals, and recording such signal through audio or visual meanswhile such bio-assay system is maintained in a controlled environment.

It is still a further object of the present invention to provide asystem as last described in which the specimen may be precisely andmanually positioned in relation to the transducing means, in which theenvironment for the specimen may be varied (such as through theprovision of pollutants to create a contaminated environment) and inwhich the transducer may be isolated from extraneous vibrations andacoustical noises.

Generally stated, the apparatus for sensitive measurement and recordingof physiological activity in a biological specimen of the presentinvention includes means for maintaining a controlled environment inwhich the specimen may be mounted, means for stereotaxically mountingthe specimen, transducing means mounted so as to minimize vibration,electrical means for amplifying and filtering signals produced by thetransducing means to permit selection of desired signal frequencycomponents, and means for recording the physiological activity of thespecimen represented by the electrical signals.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of anexemplary environmental chamber constructed in accordance with thepresent invention;

FIG. 2 is a schematic electrical diagram of the apparatus for measuringand recording physiological activity of biological specimens; and

FIG. 3 is an enlarged elevation view of the means for supporting thebiological specimen during operation of the apparatus.

DETAILED DESCRIPTION Referring now to the drawings, there is shown inFIG. 1 an exemplary apparatus for sensitive measurement and recording ofphysiological activity of a biological specimen which includes anenvironmental chamber 10 as seen from FIG. 1 and which is illustrateddiagrammatically in FIG. 2. Such environmental chamber includes meansfor maintaining a controlled environment in which the specimen may bemounted including base 11 and a glass or plastic hemispherical cover 12which is mounted above the base 11 and is in sealing contact therewiththrough a sealing strip 13 to form a hermetically sealed chamber inwhich a specimen may be mounted. It will of course be understood thatthe particular shape of the environmental chamber is not critical to thepresent invention nor is a transparent material necessary for thehousing although visual observation of the specimen and the chambercomponents is desirable. It is also desirable to form the cover ofmaterial which will isolate the interior of the chamber from externalundesirable noises and vibrations. The cover 12 is mounted to thehousing 11 through a conventional hinge 14 which provides access to theinterior of the environmental chamber. Through the provision of theacoustically and atmospherically isolated region, the measuring andrecording of the physiological activity of the specimen underconsideration is greatly enhanced.

The apparatus also includes means 15 in the environmental chamber forstereotaxic mounting of the specimen within the controlled environment.Such means, in the exemplary embodiment, comprises a vertically disposedpedestal 16 which passes through an opening 17 in the upper wall ofhousing 11 so as to project within the acoustically and atrnosphericallysealed chamber. A support plate or member 18 is mounted at the upper endof the pedestal 16 for direct support of the biological system beingtested. As seen in FIG. 3, the support plate 18 may be provided with awire specimen holder 19 that may be shaped for proper positioning ofvarious types of specimens. The lower end of the pedestal 16 isconnected to means for moving the pedestal in three planes through themanipulation of control knobs 20 which pass through suitable openings inthe side-walls of the housing 11. The knob shafts are connected throughgears or the like to the base of the pedestal in a manner well known inthe art for rotating the support member 18 and moving it up and down,forward and backward, or to the left and right. The means will thus beseen to allow precise positioning and movement of the specimen throughmanual manipulation completely exteriorly of the chamber.

The apparatus also includes electro-mechanical transducing means 22 ofconventional construction including a body 23 connected through suitablelead wires 24 at the rear end thereof to the electrical means to bedescribed hereinafter, such wires passing through a sealing grommet 25secured in the upper wall of the housing 1 l. The forward end of thetransducing means, which may be of the piezoelectric type, supports aneedle-like, thin, elongated, metal rod or probe 26 for engagement withthe biological specimen. As is well known in the art, the probe 26 maybe extremely sensitive to mechanical movement of its free end andthrough the piezoelectric crystal may transduce such mechanical movementinto electrical signals. The transducer body 23 is supported by aninverted U- shaped support member carried by the upper wall of thehousing and supporting the transducer body in fixed position. Thesupport 27 minimizes the transmission of vibrations from the housing tothe transducer pickup probe 26 through the provision of suitable dampingmembers which may include elastomeric mounting pads such as is shown at28.

The apparatus for maintaining a controlled environment may additionallyinclude means for introducing a selected gas into the environmentalchamber. Such means, in the exemplary embodiment, may include an inletpipe 30, the free end of which projects above the top wall of housing 11and an outlet tube 31 which projects upwardly through an opening in thetop wall of the housing into the chamber enclosed by the cover 12. Asuitable valve (not shown) may be mounted between the inlet and outlettubes within housing 1 I and may be a conventional one-way valve. Thegas to be introduced into the enclosed chamber may be contained in anypressurized source suitable for storing such gas and preferably having arubber outlet tube the free end of which may be forcibly fit over thefree end of the inlet tube 30 so that the pressurized gas source mayforce the gas into the specimen chamber. To prevent overpressurizationof thechamber, there may be provided a one-way flapper-type valve 32mounted in cover 12.

Referring now more particularly to FIG. 2, there is diagrammaticallyillustrated electrical means for transmitting and processing the signalsproduced by the electro-mechanical transducer and electro-mechanicalrecording means to facilitate the sensitive measurement of biologicalactivity and to precisely record such measurements. More specifically,the exemplary embodiment of such means includes electrical means 35 foramplifying signals produced by the transducer 22. The details of suchelectrical amplification device need not be further discussed since suchdevice may be of conventional commercial construction thecharacteristics of which will be well known to those having or dinaryskill in the art. The apparatus also includes lownoise signal frequencybandpass means 36 for selection of desired signal frequency componentsas required for analysis of the physiological activity. Such bandpassfilter may be of conventional construction.

The apparatus also includes means indicated generally at 37 forprocessing the signal produced by the piezoelectric device. Suchprocessing means may include a plurality of switches 38 for'passing thesignal through one or more of several electrical circuits such as amultiplication circuit 39, adifferentiation circuit 40, a combinedmultiplication and differentiation circuit 41, an integration circuit42, and a combined multiplication and integration circuit 43. it will beapparent to those having skill in the art that such circuits are onlyexemplary of the electrical circuits which may be pro vided to processthe signal to obtain a desired signal output for recording. Details ofsuch circuits are not given herein inasmuch as such circuits areconventional and well known in'the art.

The processed output signal is passed to a signal amplitude controldevice 45 for selecting a desired amplitude of the process signal to berecorded. Such control device is manually operable and may be controlledby a foot pedal or the like to facilitate operation of the entireapparatus. The output of the control device is passed to recording meanswhich may comprise one or more readout devices such as a permanentvisual readout device in the form of a pen chart recorder 46 of standardand conventional construction. Alternatively, or additionally, theoutput signal may be fed to a pair of earphones indicated at 47 forauditory recording of the specimen activity, or to a voltmeter device.

It should also be understood that a second, parallel electro-mechanicalmeans may be provided for transmitting, processing and recording theelectrical signal after amplification so as to provide simultaneous dualrecording of two different selected functions of physiological activityof the specimen. Such dual electro-mechanical path will include anadditional signal processing unit such as that shown at 47 and a levelcontrol device such as that shown at 45 and the incor poration of a penchart recorder having two independently activated pen devices.

The apparatus may also be provided with a thermistor element mounted inthe chamber for precision sensing of temperature and through the meansof a conventional bridge circuit displayed on a panel for observation.The apparatus may also include means for illuminating the specimen andfor optical magnification of the specimen to permit viewing by theoperator during experimental tests.

In operation, the cover 12 is lifted to provide access to the specimenholder and a suitable specimen such as the abdomen of a honeybee may bemounted on the holder for testing. The cover may then be closed and asuitable atmosphere may be created within the chamber as required forthe particular study. Through the manual control knobs 20, the pedestalmay be positioned as desired so as to move the specimen into contactwith the electro-mechanical transducer probe 26. Such positioning devicewill assure repeatable positioning in drug-chemical experiments wherethe relationship between the probe and the specimen must be consistentlymaintained in repetitive experiments to provide a common basis forevaluation. Where drug chemical experiments are conducted, the substancemay be hand administered to the specimen after it is appropriatelymounted and before closing the cover 12.

After the specimen and probe are positioned and the desired chemical ordrug substance is administered or a sample gas environment is createdwithin the chamber, the signals produced by the transducing device willbe amplified and subsequently processed as desired by the operator.Various components of the complex signal may be viewed and recorded atthe same time including duplication and inversion. Moreover, the chartrecorder may be two-speed permitting further flexibility in the mannerin which the signals are recorded for evaluation.

The apparatus has been demonstrated for use in testing the reaction andfate of classical depressants and stimulants, for the determination ofcyclic rhythms in individual organs of unstressed honeybee abdomens, andfor the qualitative and/or quantitative evaluation of drug substances aswell as the physiological responses to dissolved contaminants inpolluted air and water. Thus, the exemplary device herein described willbe seen to accomplish the objects as previously set forth for providinga sensitive measuring and recording device to determine thephysiological activity and responses in a biological specimen. While theforegoing detailed description has been made with reference to anexemplary embodiment of such an apparatus in accordance with the presentinvention, it should be noted that other embodiments and variations,modifications and alterations thereof may be made within the scope ofthe present invention.

I claim:

1. In an apparatus for sensitive measuring and recording of thephysiological activity of a biological specimen mounted in anatmospherically and acoustically s aled chamber on a manua llyositionable pedesta and in engagement with a rxe y mounted piezoelectricprobe, the improvement comprising:

electro-mechanical means for transmitting, processing and recordingsignals produced by the probe due to the physiological activity of saidspecimen including, signal amplification means, low-noise bandpassfilter means, means for processing the signal by selectivemultiplication, integration or differentiation of the signal, and meansfor recording a selected function of physiological activity of thespecimen.

2. Theimprovement of claim 1 wherein including a second parallelelectro-mechanical means for transmitting, processing and recording thesignal after amplification to provide simultaneous dual recording of twodifferent selected functions of physiological activity of the specimen.

3. An apparatus for sensitive measurement and recording of physiologicalactivity and responses in a biological specimen stimulated by controlledsources comprising:

means for maintaining a controlled environment including the chemicalcomposition of the gas in which the specimen is mounted;

electro-mechanical transducing means responsive to the physiologicalactivity of said specimen including means for fixedly supporting saidtransducing means within said environment and so as to minimizevibration thereof;

stereotaxic mounting means for said specimen within said controlledenvironment including means exterior of said environment for manuallycontrolling the precise position of a selected portion of said specimenin engagement with said transducing means;

electrical means for amplifying signals produced by saidelectro-mechanical transducing means;

electrical signal frequency bandpass means for selection of desiredsignal frequency components; and

means for recording the physiological activity and response of thespecimen represented by said signal.

1. In an apparatus for sensitive measuring and recording of thephysiological activity of a biological specimen mounted in anatmospherically and acoustically sealed chamber on a manuallypositionable pedestal and in engagement with a fixedly mountedpiezoelectric probe, the improvement comprising: electro-mechanicalmeans for transmitting, processing and recording signals produced by theprobe due to the physiological activity of said specimen including,signal amplification means, low-noise bandpass filter means, means forprocessing the signal by selective multiplication, integration ordifferentiation of the signal, and means for recording a selectedfunction of physiological activity of the specimen.
 1. In an apparatusfor sensitive measuring and recording of the physiological activity of abiological specimen mounted in an atmospherically and acousticallysealed chamber on a manually positionable pedestal and in engagementwith a fixedly mounted piezoelectric probe, the improvement comprising:electro-mechanical means for transmitting, processing and recordingsignals produced by the probe due to the physiological activity of saidspecimen including, signal amplification means, low-noise bandpassfilter means, means for processing the signal by selectivemultiplication, integration or differentiation of the signal, and meansfor recording a selected function of physiological activity of thespecimen.
 2. The improvement of claim 1 wherein including a secondparallel electro-mechanical means for transmitting, processing andrecording the signal after amplification to provide simultaneous dualrecording of two different selected functions of physiological activityof the specimen.